Facebook has removed nearly 200 social media accounts linked to white supremacy groups that planned to encourage members to attend protests over police killings of black people — in some cases with weapons.

During any disease outbreak, epidemiologists want to quickly figure out whether superspreaders are part of the picture. Their existence can accelerate the rate of new infections or substantially expand the geographic distribution of the disease.

Apple's iPhones and iPads have gotten free software updates, including battery improvements and a smarter virtual assistant. The new features and capabilities in the update, iOS 9, are primarily refinements rather than anything transformative.